Calorimeter



H. JUNKERS April 9, 1935.

CALORIMETER Filed July 6, 1931 /nvenfon.-

Patented Apr. 9, 1935 UNITED STATES;PATENTPOFFICE v (JAL'ORIMETER HugoJunkers, Dessau Gern 'any, Application July 6, 1931, Serial No.548,94

InGermany July 14,. 1930 13 Claims. (o1. 73- 184) My invention relates to Calorimeters and more particularly to calorimeters oi the liquid-flow type in which the heatingvalue of fuels is ascertained by continuous combustion and the rise in the tem- 5 perature of the flowing liquid, usually water, is a measure for the heating value of the'fluids. It is an object of my invention to design a calorimeter of the type referred to for ascertaining the net heating value of fuels, i. e. the total heating value, minus the heatfor evaporating the: water of combustion. Water vapor invariably forms upon the combustion of gases which contain free or combined hydrogen. If the hot products of combustion are cooled down tothe ambient temperature, the water vaporis condensed, the heat of condensation is liberated and the total amount is equal to the heat deliveredby the gaseous constituents plus the" heat ofcondensation. Howi s ever, in the operation of furnacesby the come bustion of gas, the products of combustion are purposely not cooled with the water vapor is condensed, as the condensate would corrode the heating surfaces, and therefore opinions differ as to whether calculations of economy for furnaces should be based on the total heating value or on the net heating value. The argument in favor of the total heating value is that it is more scientific because the maximum heat extraction is that in which the gases'are cooled to the ambient temperature. On the other hand, it is argued in favorof the net heating value, that in the actual operation of a furnace the'products of combusticn are never cooled to the ambient temperature, for the reason stated. In view of this difference of opinions as to which heating valueshould be ascertained, it is desirable to provide, in addi-' tion to the old caiorimeters for directly ascertaining the total heating value, a calorimeter in which the net heating value is ascertained rapidly, continuously and exactly. I

In reducing my invention to practice," I provide means for effecting a flow of liquid, usuallywater, in heat-exchange relation to the products of cominlet and at the outlet for the liquid as in the normal operation of calorimetersbut according to my invention I provide means for re-evaporating the water of combustion which has condensed from the-products of combustion after they have given up their heat to the liquid in the heat eX- changer. The rte-evaporation of the, condensate may be effected by heat extracted from the products of combustion or by a separate source of heat. If the heat for re-eva'porating the condensate is extracted from the products of combustion, for instance by providing a heating coil for the condensate in the immediate vicinity of the test flame, the amount of heat which is effective on the heat (30 exchanger and is measured by the temperature bustion and for measuring the temperatures at the gradient from the inlet to the outlet of the cooling medium, is the total heating value minus the heat recovered therefrom for re-evaporating the condensate. 1

Instead of re-evaporating the condensate by heat from the test flame, i. e., by heat supplied to the calorimeter by the fuel under test, I may re-evaporate the condensate by means of heat from a foreign source and recondense the steam by means of the flowing liquid on its way to, or on its way from, the calorimeter. The temperature of the flowing liquid is obviously increased by the heat liberated during re-condensation and the amount of heat corresponding to this inoreaseqof temperature is the heat recovered by the evaporation of the condensate which subtracts from the total heating value sothat the net heating value is the result.

Normallythe temperature gradientis measured directly, for instance by means of an air thermometer, but it mayalso be measured indirectly by means of thermocouples, resistance thermometers and the like. i I h r In an apparatus having-a foreign source of heat two sets of thermocouples maybe provided.

thefirst set measuring the heat of combustion corresponding to the total heating value, the second set being influenced by the temperatures of the flowing liquid at the inlet and at the outlet of the condenser for re-condensing the evaporated water of combustion.

thermocouples are connected in opposite relation and the difference between their voltages-indi cates the netheating value.

The foreign source of heat involves-a somewhat higher initial cost of the apparatus than the re-- evaporation of the condensate by the partly'rcovered heat gofthe tested fuel itself, but it presents the advantagethatthe total and net heating values are ascertained simultaneously and may be indicated or recorded side by side. From Fig. 2 is a partly sectional elevation of a calorimeter in which a separate source of heat is provided for evaporating the condensate.

, Referring now to thedrawing and first to Fig.

1, the heat exchanger l: of the calorimeter is heated by the flame of a burner 2 to which fuel,

inthe present instance, gas, is supplied. The

gases of combustion give up their heat to the flowmy invention are illustrated diagrammatically 145 condensate from the tubes 5!, and from which the gases of Combustion are discharged by a chimney flue 3.

5 is a reservoir for the water which flows in'th'e' heat exchanger I, t is a supply pipe connected to the reservoir, 1 is a down-flow pipe, with an enlarged casing 5i and a thermometer 52, extending fromthe reservoir 5 to a point near the bottom of the heat exchanger, 8 is thedischarge pipe for the water at the upper end of the calorimeter, and i3 is a thermometer connected to this p pfi Bis a weir in'the reservoir 5, 9 is a downflow pipe for the reception of the water overflowing the weir, and it is an aspirator which is connected to the collector 53 through a pipe iii, a coil H which is heated by the flame of the burner 2, a

pipe l lconnecting the coil l l to the bottom of the a collector 53,-and a three-Way cock E5 in the pipe M which also serves for draining the condensate. ,Water is continuously supplied to the reservoir v5 through the pipe .6, descends to the heat exchanger through the downflow pipe '5 and is discharged through the pipe 8. In this manner, a continuous flow of liquid through the exchanger 1 is established. A portion of the water in the reservoir 5 flows over at the weir 6 and operates the aspirator' H3. Under the suction of theaspirator, the condensate from the collector flows to the coil ll through the pipe i i and the threeway cock is and is evaporated in the coil.

The vapor from-the condensateflows to the aspirator l0 through-pipe E9 and is condensed by the water descending in thepipe i3.

, By evaporating the condensate in the coil ll the heat for the evaporation of the condensate subtracts from the total heat of the products of combustion'sothat now only the amount of heat corresponding to'the net heating value is given ofi to the water in the heat exchanger 13. The difference between the indications of the thermometers l2 and 3 at the inlet and'atthe outlet 'of the Water, multiplied with the quantity of water flowing through the calorimeter per unit of fuel,

is a measure for the net'heating value. If it is condensate is drained from the is chosen slightly above the minimal value redesired to ascertain the total heating value the collector 53 through the thI'GS-WQY'COCK I 5.

The pipe M is a siphon in which forms a liquid seal oi condensataso that gasis not drawn into theaspirator it. The suction of the aspirator it quired for'raising the condensate from the bottom of the collector 53 to the evaporator i i In order, however, to avoid sucking of the whole liquid from the collector 53 causing a sucking in of the gases of combustion alone, the pipe it is formed as a loop, the length of the shanks of which is chosen in such amanner that the aspirator cannot suck the .entire liquid from'the collector Since a suc i force of the aspirator, equivalent to a few centimetresof head of water, is sufiicient, the shanks require merely a length of a few centimetres. Preferably the loop is made as short as possible in order to avoid a lagging or" the indica .tion due to the contents of liquid in the loop.

- Even if accidently gasis drawn into the aspirator It, this will not influence the test result to any 7 appreciable extent as the heat which this gas can absorb, is practically nil as compared with the heat required for evaporating the condensate in 53 is an annular collector at the lower through the discharge pipe 3.

about 1/2 000 ,000 of the evaporation heat of water 7 related to equal volumes. Assume, for instance, that equal volumes of gas and water are admitted to the evaporator, and that thegas and the water areheated to about 100, one cubic centimetre of water absorbs about GOO/1060:.6 calories for evaporation, while one cubic centimetre of gas absorbs (.3 100) /l 000 000:.0GGO3 calories, the-coefficient .3 being the specific heat of one cubic metre of gas. The gas, consequently, absorbs only 1/20 000 of the heat absorbed by the evaporated 'watenso that, even if some bubbles of gas are accidentally entrained, the result will not be appreciably influenced thereby.

In Fig. 2 the heat exchanger E,.theburner 2,

and its other accessories are designed asdescribe'd with reference to Fig. l, and the products of 001115 bustion are carried away from the annular collector 53 through the flue 3; J it is a water meter L- below the reservoir 5, with an outflow pipe 3i, and i 9 is a gas -i eter which is connected to the water meter by suitable positive means such as a sprocket chain 52, so as to maintain constant the ratio of gas and water.

The water froi'n the water meter,

ill fiowsto the heat exchanger through pipe l and casing 57. The thermometers IE or" pipefl, and

in the discharge'pipe 8, are here replaced by a thermoelectric system having a thermocouple 41 in the casingtl' where it is under the influence or" the cold Water flowing in the pipe 1', and another thermocouple 'll in the flow of the heatedwater eter to which: the couples 4!, 4! are connected. is a chamber with another thermocouple 38 arranged in'the pipeB." 26 is a condenser, to the 'which the water from the pipes 3i and 33 is delivered; 25 is a liquid heater, preferably with an insulating jacket, 25 is a burner for heating t--e liquid in the jacket, and 255 is a filling and expansion tank at'the top of the 'heater 25. siphon'p'ipe connected to'the'condensate collector 53 at the base of the heat exchanger 5 at one end so as to form a liquid seal, 22 is an upwardly directed vertical reach of the siphcn pipe which 52 is a galvanonn. V

partly extends through the water space of the" heater 25, and Z3 is a downwardly directed vertical reach of the siphon pipe'which partly extends through the; cooler 26 and at its lower end delivers intothe reservoir 30; The condensate from the collector 53 enters the left shank of the siphon pipe 2! and a corresponding amount of liquid flows from the upper end of the right shank of the siphon pipe through the inclined connection connecting the siphon to the vertical reach 271, this amount of liquid being vaporized in the knee forming the lower endof the reach 22, so that only vapor. rises in the vertical reach 22 in the heater 25. The vapor is re-condensed in the-reach 23 by the condenser 20, and the "final condensate delivered to thereservoir 39. 1 The liquid in the heater 25 ishea-ted to a tern perature which is higher than that requiredior the complete evaporation of the condensate. This excess temperature is required in order to evaporate all the water in the vertical reach 22 of the siphon pipe, .The excess of temperature, howthat there will be no heat ,burner to the siphon. siphon, providedthat theshanks of the siphon 1 are long enough, willnot allow gas to make its way through the siphon, but even if, by accident,

' a few gas bubbles make their way through the tor superheat is so small as compared with'the evaporation heat that it will not appreciably raise the temperature in the condenser 29 and the test re- ,sult will not be influenced by this negligible temperature :rise. Obviously, evaporation of the water in the siphon Tall is impossible, the more so as the siphon isIat such a distance from the burner 'ransfer from'the Normally, the water in the Water in the siphon, this is'practicallyavithout importanceas explained with reference to Fig. 1.

The temperature regulator controls plete evaporation of the condensate.

The recondensation of the evaporated .con-

densate in' the condenser ze-involves an increase of temperature of the "cooling "fluid flowing through the condenser 29. The heat transferred to the cooling medium in the condenser ZDis measured by the thermocouples 38 and 38' con nected to the galvanometer t3.

the couples 3% and 38 is'opposed to thevoltage of'the couples ti and 4twhich measure the increase of temperature due to thecombusticn in the burner 2. indicates the difierence between the voltages at 45, 4! and 38, 38' respectively and thereby directly the net heating value; while the galvarnometer 32, whi h is connected. only to the cou The voltage of The galvanorneter 5% therefore ples il, ii, indicates theCtotal heating value.

The variations of the heating value occurvery gradually so thatthe slight lag between the indications at the thermocouples 'M-45 and Bil-48 is ,Withoutinfluence on the final indication of thefnet heating value.

Variouschanges may be made in the details disclosed in the foregoing specificationwlthout departing from the invention or sacrificingthe advantages thereof.

l. A calorimeter of the liquid-flow type for aspertaining .thenet heating value of fuels by continuous combustion, comprising a burner, means for, supplying to said burner. the fuel to; be'tested,

a heat exchanger adapted to be heated by the products of combustion from-said burner, means foreifecting a continuous flow of liquid through said heat exchanger, meansfor measuring the rise of temperature of the liquid flowing in said is a supply pipe to the burner 24 in i the liquid heat-er 25,?whiclo is preferably'connected toa temperature regulatorZl. Q i I the fuel supply to the burner 2% so as toheat the liquid in the heater 25' toa temperature whichis somewhat higher than. that required for the comheating said evaporator.

' den'sation'. a v 6. A'calorimeter of the liquid-flow type for means forsupplying to saldburner the fuel to be tested, a heatfexc'hanger adapted to be heated by the products of combustion from said burner; 'meansfor effecting a continuous flow of'liquid ,throughfsaid heat exchanger, means for measur ing the'rise oftemperature of the liquid flowing in saidsheat. exchanger, means for collecting the condensate which separates from the products of combustion in said heat exchangeryan.evaporator for continuously. re-evaporating the condensate, and aniaspirator operated by a portion of the rliquid' for conveying the condensate from said collecting means to said evaporator,

V certaining the net heating value of fuels by con- 3 tinuous combustion; comprising a burner, means for supplying to said burner the fuel tobe tested,

a heat exchanger. adapted to-be heated by the i products of combustion from said burner, means for effecting, a' continuous flow of liquid through said heatexohanger, means for measu -ing the rise oftemperature of the liquid flowing in said heat exchanger, meansforcollecting the condensate which separates from the products 'of combus-,

tion' in said heat exchanger, an evaporator. for continuously re-evap'orating the condensate and means for conveying" the condensate from said collectingmeans to said evaporator, saidevaporator being arranged so astobe heated by said burner. i

4. A calorimeter. of the liquid-fiow tyne for ascertaining the net heating value of fuels by by the products of combustion from said burner,

means for effecting acontinuous flow of liquid through said heat exchanger, means for measuring the rise of temperature of the liquid flowing in said heat exchanger, means for collecting the densata means for conveying the condensate from said collecting means to said evaporator, and a source of heat independent ofi said biu'ner for A-calorimeter of the liquid-flow type for ascertainingthenet heating value of fuelsby continuous combustion, comprising a burner, means for supplying to said burner the fuel to be tested, a' heat exchanger adapted to be heated by the products of cornoustion'from said burner, means for effecting a continuous flow of liquid through said heat exchanger, means responsive to rise of temperature of the liquid flowing in said heat exchanger, an evaporato'r'for continuously reevaporating the condensate which separates from,

the products of" combustion in said heat ex- "condensate which-separates from the products ofcombustion in said heat exchanger; evapj orator for continuously re-evaporating the-con burner for heating :said evaporator, acondenser, means forcor'iducting through said condenserthe liquid flowingiin said heat exchanger for re-c'on- (lensing the re-evaporatedcondensate, and means for measuring the'heat liberated by such reconproducts of combustion from saidburner, means for effecting acontinuous flow of'liquid through said heat exchanger, meansresponsive to the rise of temperature of the liquid flowing in said heat exchanger, an! evaporator for continuously reevaporating the condensate which separates from the products of cornbustion'in said heat exchanger, a source of heat independent of said --burnerfor heating said evaporator, a condenser,

means for conducting'through said condenser the liquid flowing in said heat exchanger, means resp'onsive to the temperature rise or the liquid iflowing'through said condenser, means connecting said temperature-responsive means at said heat exchanger and at said condenser, and indicating means connected to said connecting means "for readingthe temperature rise corresponding to the net heating value.

'7. A calorimeter of the liquid-flow type for as-{ certainin'g the net heating value of fuels by continuous combustion, comprising a burnen'means for supplying to said burnerthe fuel to be tested, a heat exchanger adapted to be heatedbythe products of combustion from said'burnenfmeans for effecting acontinuous flovv'of liquidithrough said heat exchanger, thermocouples connected in seriesand responsive to the rise of temperature of the liquid flowing in said heat exchanger, an evaporator fcricontinuously re-evaporating the "condensate which separates from the products of combustionin said heat'exchanger, a source of heat independent of saidburner for heating said evaporator, a condenser, means for conducting through said condenser the. liquid flowing from said heat exchanger, another set of thermocouples connected in series and responsive to the temperature rise of the liquid flowing through said condenser, a connection between said thermocouple which is so designed that the electronictive forces of the thermocouples at the heat exchanger and at the condenser are oppositely directed, and means connected to said, couples for reading the temperature rise corresponding to the net heating value.

8. A calorimeter of the liquid flow ype forescertaining the net and total heating value of fuels by continuous combustion, comprising a'burner,

' means for supplying to said burner the fuel to be tested, a heat exchanger adapted to be heated by the products of combustion from said burner, means for effecting a continuous flow of liquid through said heat exchanger, means for measuring the rise of temperature of the liquid flowing in said heat exchanger, an evaporator for continuously re-evaporating the. condensate which separates from the products of combustion in said heat exchanger, andmeans for measuring the heat required for the re-ev'aporation independthe liquid flowing in said heatexchanger, an

evaporator for continuously re 'evaporating the condensatewhich separates from the products of combustion inisaid heat exchanger, a source of heat independent of said burner for heating said evaporator, and means for measuring the heat required for there-evaporation independently of said temperature-responsive means.

[19. A calorimeter of the liquid fiow type for ascertaining the net heatingvalue of fuels by continuous combustion, comprising a burner, means i for supplying to said burner the fuel to be tested,

a heat exchanger adapted to be heated by the products of combustion from said burner, means for effecting a continuous flow of liquid through said heatexchanger, means for measuring the i temperature rise of the liquid flowing in said heat exchanger, an evaporator for continuously re-- evaporating the condensate which separates from the products of combustion in said 'heatexchanger, a source of heat independent of said burner for heating said evaporator, a condenser,

means for conducting through said condenser the liquid flowing in said'heat exchanger, automatic means for subtracting the temperature rise of the liquid flowing through said condenser from the temperature rise of the same liquid the heat exchanger, and indicating means operatively connected to said subtracting means for reading the temperature diiierencea f r lhA calorimeter of the liquid-flow type for ascertaining the net heating value of fuels by continuous combustion, comprising a burner,

means for supplying to said burner the fuel to be tested, a heat exchanger adapted to beheated by the products of combustion from said burner, means for-effecting a continuousflow-of liquid throughsaid heat exchanger, a collector for the CC-DL sate which separates from the products of co:

suring the ten" iature rise of the liquid flow- 1 in said-heat exchanger, an evaporator arranged at a higher level than-said collector for continuously "re-evaporating the condensate, and

means for effecting a flow of the condensate through said evaporator.

g 12. A calorimeter of theiliquid-flow type for ass certaining the net heating value of fuels'by con tinuous combustion, comprising a burner, means for supplying to said burner the fuel to'be'tested, aheat exchanger adapted to be heated by the products of combustion from said burner, means for'efiecting a continuous flow of liquidfthrough said heat exchanger, a collector forjthe condensate which separatesfrom the productsof com bustion in said heat exchanger, means formeasure ing the temperature'rise of the liquid flowing in said heat exchanger, an evaporator arranged at a higher level thansaid collector for continuous- 1y re-evaporating the condensataa'nd an aspirator operated by flowing liquid for-effecting a flow of the condensate through said evaporator;

13. A calorimeter or the liquid flow type foras certaining the net heating value of fuels by continuous combustion, comprising a burner, means for supplying to said burner the fuel to be tested;

a heat exchanger'adapted,to ,be.hea'ted by the products of combustion from said burner, means for effecting a continuous iiow'o'f liquid through" said heat exchanger, means for collecting the condensate which separates from the products 'of combustion in said heat exchanger, an 'eVapOIator for continuously i e-evaporating the condenhustion in said heat exchanger, means for,

sate, means for conveying thecondensate froni said collecting means to said evaporator and indieating means responsive to the rise of tempera ture of the liquid flowing in-said heat exchanger and operatively connected to said evaporator so as to be acted upon'by the differenceof the heat fed by the'combustion of the fuel in said burner and of the heat required for 're-evaporating the condensate in said evaporator. i

HUGO 'JUNKERS. 

